聚对苯二甲酸乙二酯的结晶与取向

为了了解PET球晶的拉伸性能与球晶结构的关系以及无定形PET的取向和结晶,我们采取了两条不同的路线来制备样品:(1)先用溶液浇铸成膜的办法制备具有正球晶、负球晶或非常球晶的薄膜,然后进行单轴拉伸。电子显微图象及电子衍射证明,球晶的拉伸性能与C轴和球晶半径方向的夹角有关,夹角愈大拉伸愈困难;(2)先制备无定形的薄膜,然后在玻璃化温度附近进行单轴拉伸以获得C轴取向,再在215℃退火,使之结晶。电子衍射图证明,这样制备的样品具有高度的C轴取向。DSC结果表明,结晶的完善程度远比球晶的为高。     

THE ORIENTATION AND CRYSTALLIZATION OF POLYETHYLENE TEREPHTHALATE

The drawing behavior of three types of PET spherulites and PET amorphous samples have beenstudied. Two different sample preparation techniques were used in this study: (1) The films withnormal positive, normal negative or abnormal spherulites were prepared by solution casting tech-niques, then the films were deformed by uniaxial drawing. The uniaxial drawing behavior of PETspherulites appears to be dependent on the angles between the c-axis and the radius direction of thespherulites and that the deformation of spherulites becomes more difficult the larger the angles. (2)Amorphous films of PET were prepared first, then the films were deformed under uniaxial drawingto achieve c-axis orientation at a temperature near the glass transition temperature. The orientedfilms were subsequently annealed with fixed length at 215℃The films prepared in this way ex-hibit excellent c-axis orientation along the stretching direction. The degree of perfection of thecrystalline structure is much greater than that of the spherulites.